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Why do smartphones explode?

The end of the summer 2016 has got a lot hotter with several “explosions” of the Note7, but how can a smartphone explode? Can any phone explode? At best, you probably know already that the most dangerous part of a phone is the battery, however we are going to see in detail how these cases could arise and also what safety measures need to be taken.

How can the battery of a smartphone explode?

The batteries that our smartphones currently use (and the majority of electronic devices too) and contain inflammable components. They are lithium batteries, both Li-ion and Li-Po. All batteries have a cathode and an anode (positive and negative), a substance which reduces and gives out electrons and another which oxidizes and collects them. This transfer is used to provide the smartphone with energy.

In all batteries, the cathode and the anode are separated by a membrane. If the cathode and the anode touch each other then they react chemically, and in the case of lithium batteries that reaction is very quick. It isn’t a strong explosion, but rather a very quick combustion. Luckily the battery doesn’t have sufficient fuel to explode violently but it will cause damage to anything within a radius of half a meter.

Batteries have three layers (cathode, membrane and anode) rolled up several times on themselves in such a way that the cathode and anode never touch. The problem arises when the membrane that separates them deteriorates or what is much worse, when it comes faulty from the factory as in the case of the Note7.

If the membrane that separates the cathode and the anode of the battery deteriorates, both of them will enter into contact and the battery will burn

All lithium batteries have a temperature control circuit. If the battery heats up above a certain temperature range then the circuit will stop it from charging. High temperatures damage the membrane and as soon as this lets the cathode and anode touch each other the combustion begins.

Can any smartphone explode?

Our smartphones seem to be harmless objects but there is latent danger inside. In general the cases of smartphone combustion are only a handful, counted in tens, whereas 1,400 million devices are sold each year (smartphone sales for 2015). So the probability that a smartphone will go up in flames is extremely low, almost the same as being struck by lightning.

So, are we in danger? Clearly not. But it is true that it can happen, however in general, quality controls ensure that batteries are safe.

If a manufacturer detects that a series of their batteries has some production fault, it will withdraw the devices immediately. Just as Samsung has stopped the distribution and withdrawn the faulty models of the Note7.

Anyway, it’s always good to keep an eye on our batteries. We should make sure that they never exceed 60 degrees. If it starts to swell or deform it should be changed immediately. And what must never be done is pierce them with a sharp object as shown in the video above.

In cases like the Note7 in which the manufacturer acknowledges the mistake and orders the terminals to be returned, we should stop using the device immediately, not charge it again and follow the protocol that the manufacturer stipulates.